let x1, x2, y1, y2;
let cx1, cy1, cx2, cy2;
let res_left, res_top, res_right, res_bottom;
let rotationAngle = 0;   //旋转的角度
const divElement = document.getElementById("rect");      // 拉取出来的框
const imgElement = document.getElementById("chrome_img");                  // 预览框dom
const scanResElament = img                                               // 拍照结果显示框dom
let zoomScaleVal  //缩放比
let soureDevHeight, soureDevWidth //获取当前分配率;
let num2 = 400;   //比例


